The 131-year-old film giant filed in the federal bankruptcy court in the Southern District of New York. The filing, which only includes Kodak's U.S. subsidiaries, listed assets of $5.1 billion and debts of $6.75 billion.

Kodak had said back in November 2011 that it would be unable to pay its bills at some point in 2012 unless it stumbled into some quick cash. The company needed at least $500 million to stay afloat through the year, and it tried to sell its portfolio of 1,100 digital imaging patents in order to raise some cash, but was unsuccessful in doing so.

"Kodak is taking a significant step toward enabling our enterprise to complete its transformation," said Antonio M. Perez, chairman and chief executive officer of Kodak. "At the same time as we have created our digital business, we have also already effectively exited certain traditional operations, closing 13 manufacturing plants and 130 processing labs, and reducing our workforce by 47,000 since 2003. Now we must complete the transformation by further addressing our cost structure and effectively monetizing non-core IP assets. We look forward to working with our stakeholders to emerge a lean, world-class, digital imaging and materials science company.

"After considering the advantages of chapter 11 at this time, the Board of Directors and the entire senior management team unanimously believe that this is a necessary step and the right thing to do for the future of Kodak. Our goal is to maximize value for stakeholders, including our employees, retirees, creditors, and pension trustees. We are also committed to working with our valued customers."

Kodak said it expects to continue operating normally while in Chapter 11, including offering goods and services to customers while continuing to provide employees with usual wages and benefits.

Kodak, which received a $950 million debtor-in-possession from Citigroup in order to provide the company liquidity to operate normally during bankruptcy, aims to focus on four main goals while undergoing Chapter 11: receive financing needed to stay in business, the ability to pursue patent infringement claims, focus on the printing business (because that's where the area of growth is, according to Perez), and change its legacy costs to a "fairer level."

"Chapter 11 gives us the best opportunities to maximize the value in two critical parts of our technology portfolio: our digital capture patents, which are essential for a wide range of mobile and other consumer electronic devices that capture digital images and have generated over $3 billion of licensing revenues since 2003; and our breakthrough printing and deposition technologies, which give Kodak a competitive advantage in our growing digital businesses," said Perez.

Kodak expects to complete its restructuring in 2013. The bankruptcy filing will not affect non-U.S. subsidiaries. Kodak is also expected to announce its Q4 2011 and full-year financial results on January 26.